Iodine has been found to be an effective and economical means of water purification by disinfection. Iodine has advantages over chlorine for the disinfection of water because it does not add any color, odor or taste to the water at normal treatment levels and does not readily combine with other chemicals. Also iodine is simpler to use, require less maintenance, and is relatively more chemically inert than chlorine. Therefore it is particularly advantageous for use in purifying rural water supplies and those in developing countries. If there is concern regarding the consumption of iodine, simple carbon filtration will remove the iodine, after the initial purification step, although the water will be left without a protective residual.
Another advantage of iodine is its use as a disinfectant in association with food processing, for instance for cleaning containers or dishes. Presently iodophors are used for this purpose, i.e. iodine in combination with a detergent.
Iodine in sufficient concentration will completely inactivate the coliform group under most practical situations where total coliforms in the raw water do not exceed 1,000 per 100 milliliters (ml). Iodine will dissolve in water, provided no iodides are present, at a maximum concentration (saturation) of 147 parts per million (ppm) or milligrams per liter (mg/l) at a water temperature just above freezing and 300 ppm or mg/lat 26.degree. Centigrade. In this specification the term "above freezing" means that state where the water retains a minimum number of calories which would keep its temperature less than one degree Centigrade but which would maintain the water in a liquid state. The concentration for effective disinfection of water to render it potable is a residual of 0.5 ppm or mg/lretained for 15 minutes above 7.2.degree. C. (45.degree. F.) and 30 minutes below that temperature. Studies have indicated that such concentrations produce no harmful physiological effects to those consuming the water.
Iodine has also been found to act as a superior disinfectant for sanitizing inanimate objects where limited organic contamination may be present and where reduced occurrence of corrosion is necessary as has been determined by the U.S. Environmental Protection Agency (EPA) and the U.S. Department of Agriculture (USDA). Concentrations normally used are limited to levels of 25 mg/lor less where iodine might become an incidental additive to food products and levels as high as 75 mg/lwhere more thorough disinfection is required.
Iodine's efficacy as an anticeptic for the disinfection or sanitizing of living tissue is also well documented in the medical literature and by the U.S. Federal Drug Administration (FDA) and the U.S. Department of Agriculture (USDA). It is an object of the present invention to provide levels of iodine up to 1100 mg/lto achieve antisepsis, disinfection and sanitization as set out in EPA, FDA and USDA definitions.